Drying apparatus for asbestos or other material.



J. N. BOUHQUE.

DRYING APPARATUS FOR ASBESTOS 0R OTHER MATERIAL.

APPLICATION FILED EEB. 5,1916.

Patented Apr. 17,1917.

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JOSEPH N. BOURQUE, 0F THETFORD MINES, QUEBEC, CANADA.

DRYING APPARATUS FOR ASBESTOS OR OTHER MATERIAL.

Specification of Letters Patent.

Patented Apr. il 7, 1911. *7.

Application filed February 5, 1916. Serial No. 76,491.

To all whom it may concern:

Be it known that l, Josnri-r N. BoURQUE, a. subject of the King of Great Britain, and resident of Thetford Mines, in the Province of Quebec and Dominion of Canada, have invented certain new and useful Improvements in Drying Apparatus for Asbestos or other Material, of which the following is a full, clear, and exact description.

This invention relates to improvements in dryin'g apparatus for asbestos or other material, and the object of the invention is to provide an economically and continuously operating drier for asbestos or other material.

A further object is to provide means for preheatling and rough drying the material before entrance to the drier proper, for the joint purpose of improving the efficiency of the drier and protecting the material from injury due to sudden exposure to intense heat.

The device consists of a furnace, a tower, and a rotary dry kiln arranged between the furnace and tower. The material to be dried is delivered at the top of the tower and passes downwardly over a series of baffle plates which are arranged to retard progress and to loosen up the material sufficiently to insure a rough drying and preheating. The rotary kiln into which the material passes from the tower is provided with transporting means which operate to tumble and spread the material, so that in its passage through the kiln, all material receives equal exposure to heat. The hot gas discharged from the furnace enters the lower end of the kiln in its upper portion, while the dried material passes out under this furnace dis` charge through a suitable chute.

In the drawings which illustrate the invention:-

Figure 1 ,is a` vertical longitudinal section of the device taken on the longitudinal axis of the kiln.

.Fig 2 is a vertical cross section of the furnace on the line 2-2, Fig. 1.

Fig. 3 is a vertical cross section of the kiln on the line 3 3, Fig. 1.

Referring more particularly to the drawings, 11 designates a cylindrical kiln ar ranged at a slight inclination and mounted for revolution about its axis on rollers 12 or other suitable devices, which coperate with track rings 13 secured to the kiln. At any suitable point, the kilnis provided with a toothed ring or driving gear 1l in mesh with a driving pinion 15, which receives revolution in any suitable manner. rThe interior of the kiln is provided with a plurality of longitudinally disposed angles or ribs 1G extending substantially from end to end thereof. These ribs carry curved plates 11T, which with the ribs form a species of worm or helix designed to transport the material from the bottom to the top of the kiln with the revolution thereof, and also to spread the material over as large a surface as possible, so as to facilitate the drying effect. After the material has been raised to a certain point, it slides off the plates and falls to the bottom of the kiln. The tumbling it thus receives breaks up any lumps, and keeps the material constantly turned, so that all parts thereof receive equal drying. Owing to the inclination of the kiln, this lifting and dropping of the material causes the same to gradually work from the upper to the lower end thereof in the well known manner. The upper or elevated end of the kiln is provided with an end plate 18 having a. central opening somewhat smaller than the diameter of the kiln, while the lower or discharge end of the kiln is open to the full size of the shell.

At the upper or inlet end of the kiln, a suitable tower 19 is provided having an opening 2O for the reception of the kiln end. The interior of this tower is provided with a plurality of oppositely inclined baffle plates 21, which may be solid or perforated as desired, and which are disposed at such angles and extend such distances across the interior 0f the tower as to very considerably retard the fall of material through the tower. Material is delivered into the tower through a chute 22 having a gravity closing gate 23 at the lower end thereof for the purpose of preventing the escape of heat through the chute. The material falls from the lowest baiile plate 21 on to an apron 2l, which projects through the end plate 18 of the kiln and discharges the material into the kiln. This apron may be perforated or solid as desired. The tower may be provided with a number of suitable man-holes 25, through which access may be had to the interior of the tower when required. A flue or stack 2G leads from the top of the tower for the escape of furnace gases and waste heat. lt is preferred to face the inner surface of the tower at points where the falling material impinges with removable plates 27 for thc` purpose of protecting the tower proper from wear.

At the lower end of the kiln, a laterally directed chute 28 is set in the rear wall of the furnace 29, and is provided with an outwardly opening gravity gate 28?' designed to prevent the entrance of cold air. The rear wall of the furnace is apertured or recessed, as shown at 30, so that the end of the kiln may project thereinto.

The furnace 29 may be of any suitable type, but is preferably constructed with an arched roof 31 having a rearwardly directed outlet flue 32 formed in line with the roof, so that as much of the heat of the furnace as possible escapes through the Hue, thus reducing to a minimum the heat loss by absorption in the furnace walls. The flue 32 is of considerably less diameter' than the kiln, and projects a short distance into the upper portion of the kiln, as clearly shown, thus leaving a clear space 83 in the lower part of the kiln through which the dried material may pass to the chute 28. The dotted lines above and below the drying cylinder indicate that an insulating` jacket may be placed therearound.

In order to prevent the rush of hot gases through the kiln, sucking in cold air at the ends thereof, face plates 34C are provided around the openings 20 and 30, and the kiln is provided with annular plates 35 revolubly mounted thereon, and bearing against the plates 34;. It will be readily understood that the plates 35 being mounted on the kiln will maintain a comparatively tight joint therewith, and also with the plates 34, folding over the plates 34: if there is any slight irregularity in the movement of the kiln. It will be noted that the track rings and driving gear are provided with submountings 36 instead of being attached directly to the shell of the kiln. These mountings may be brackets or perforated plates, and the object is to prevent overheating of the track rings and gear, which would increase friction and constantly the amount of power required to drive the kiln.

The operation of the device may be readily understood. In the mining of asbestos, the material frequently comes from the pits more or less water saturated, and during the winter months is more or less snow or ice laden. The presence of this moisture renders the subsequent treatment difficult or impossible, and it therefore becomes necessary to dry the material before it can be further treated. This drying operation must be continuous, rapid and inexpensive, and must, nevertheless, be of such character as to avoid a too rapid heating. The apparatus just described has the advantage of being continuous in operation and capable of handling a large amount of material per day with remarkable efhciency. The hot gases from the furnace enter the lower end of the kiln and travel rearwardly therethrough to the tower, up which they pass to the flue or stack 26. The very slight inclination of the kiln, combined with the baffle plates greatly, retard the draft, so that comparatively speaking only a negligible amount of heat escapes through the flue 26. 1When the material is being run through the apparatus at the most suitable rate, the lumps falling from the ribs and plates in the drum form a constantly changing pervious curtain of material in the path of the heat. Naturally, the material at the lower or discharge end of the kiln strikes the gases escaping fromV the furnace. This material has had considerable heating and drying and will therefore not be injured by the high temperature. As the gases work back through the kiln more and more heat is given up to the material, so that when the gases enter the tower, there is only suflicient heat to melt accumulations of ice or snow on the material and rough-dry the same, so that it is discharged into the kiln substantially free from liquid, and very slightly warmed. As the material advances through the kiln, it absorbs more and more heat and meets with constantly hotter gases. The moisture driven olf will to a large extent escape through the flue 26 in the form of vapor, but when the material carries a large load of snow or ice, this will be merely converted into water, the largest part of which will escape through perforations in the apron.

Having thus described my invention, what I claim is:-

l. In a device of the character described, a furnace, a tower having a tortuous passage adapted for the movement of solid material by gravity extending downwardly from the top thereof, and a revoluble drjT kiln mounted between the base of said tower and the furnace, said tower and kiln forming an outlet flue for the furnace.

2. In a device of the character described, a tower, baffle plates therein forming a tortuous passage extending downwardly from the tower top, a furnace, a kiln forming connection between the furnace and tower passage, an inlet at the top of the tower, means for preventing the escape of furnace gas through said inlet, and a furnace gas outlet at the top of the tower.

3. In a device of the character described, a rotary kiln inclined slightly from the horizontal, transporting means in said kiln arranged to maintain material passing through the kiln as much as possible in the air, a furnace arranged to discharge hot gases into the lower end of said kiln, a tower arranged to convey furnace gases from the upper end of said kiln and to discharge material into the kiln, and means in said tower arranged to retard the passage of material and fur.- naee gases sulieiently to eect a rough-drying and slight preheating of the material prior to entry into the kiln.

Ll. In a device of the character described, a revoluble shell inclined slightly from the horizontal, longitudinally disposed ribs projecting from the inner surface of said shell, and eurved transporting plates carried by l0 said ribs arranged in the form -of a worm and adapted to uniformly distribute material passing through the kiln and maintain the progress thereof from the upper to the lower end of the kiln at low speed.

In witness whereof, I have hereunto set l5 Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C. 

